This invention relates generally to irrigation sprinkler devices of the type including a spray nozzle through which irrigation water is delivered in a selected spray pattern to a surrounding terrain area, wherein the arcuate width of the selected spray pattern is variably adjustable. More particularly, this invention relates to an improved variable arc spray nozzle for providing a stream or spray of irrigation water to a target terrain area with increased range and improved uniformity of water distribution.
Sprinkler spray heads or spray nozzles are well known in the art, of the type adapted for mounting onto the upper end of a fixed or pop-up water supply riser and including at least one discharge orifice shaped to distribute irrigation water in a stream or spray pattern of selected arcuate width to surrounding vegetation such as turf grass, shrubs and the like. In one common form, such spray nozzles are manufactured from relatively economical plastic to include an upper deflector assembled with a lower nozzle body for mounting onto a water supply riser, wherein the deflector and nozzle body cooperatively define the discharge orifice of selected arcuate span through which the water stream or spray is projected outwardly. Such spray nozzles are normally produced in a several standard models to respectively provide, for example, a quarter-circle, half-circle, three-fourths-circle, and full-circle spray patterns. In a typical irrigation system installation employing a plurality of spray nozzles for collectively irrigating a terrain field, a combination of different spray nozzles models are used at different locations throughout the terrain field to insure that irrigation water is distributed over the intended area, substantially without spraying water onto unintended areas such as walkways and roadways.
In many instances, however, the specific geometry of the terrain area to be irrigated has a non-standard configuration, particularly along the sides or edges of a terrain field to be irrigated, wherein use of a standard model spray nozzle will result in the delivery of irrigation water onto unintended areas or alternately will result in a spray pattern of insufficient arcuate width to irrigate the desired terrain area. To avoid water waste or inadequate irrigation of vegetation in such non-standard applications, so-called variable arc spray nozzles have been developed for providing a customized water stream or spray pattern of adjustably selected arcuate width. Such variable arc nozzles include a discharge orifice defined in part by a rotatable adjustment member for selectively re-positioning one side edge of the discharge orifice in a manner to adjust the arcuate width of the resultant water spray pattern within a substantially continuous range of from about 0.degree. to a full-circle pattern. Exemplary variable are spray nozzles are available from Rain Bird Sprinkler Mfg., Corp., of Glendora, Calif. under product designation VAN Series Nozzles. See also U.S. Pat. No. 4,579,285.
While variable arc spray nozzles beneficially permit specific custom setting of the spray pattern arcuate width, the distribution of water to the surrounding terrain from such nozzles has been relatively irregular and non-uniform. More specifically, for any selected spray pattern width, the precipitation rate for the delivery of irrigation water to the target terrain area has tended to be undesirably uneven with some zones receiving substantially more water than others. Moreover, this distribution inconsistency tends to shift in an apparently unpredictable manner as the spray pattern width is increased or decreased. In addition, near the movable side edge of the adjustable width spray pattern as defined by the rotatable adjustment member, the water distribution has a tendency to be particularly non-uniform and indistinctly defined with a significant fall-off in the projected range of throw. These characteristics have limited the commercial acceptance of variable arc spray nozzles.
The present invention relates to an improved variable arc spray nozzle designed for overcoming these problems and disadvantages, particularly with respect to delivering irrigation water in a stream or spray pattern of variably adjustable arcuate width and with a substantially uniform precipitation rate to a surrounding target terrain area.